file.sc

>>> def delay(n):
...     x = [None]*(n+1)
...     i = 0
...     while 1:
...         x[i] = yield(x[i])
...         i = (i + 1) % (n + 1)
... 
>>> f = delay(3)
>>> f.next()
>>> f.send(1)
>>> f.send(2)
>>> f.send(3)
>>> f.send(4)
1
>>> f.send(5)
2
>>> f.send(6)
3